We have a bluegill...about six inches long. Since we also have mosquito fish, ghost shrimp, tadpoles and other critters (for instance...we have a complete lack of baby goldfish in her pond, though there are lots of baby goldies in the other pond) that she can eat, I take a cue from her about when she is actually hungry. In fact, the only time I actually see her is when she wants to be fed, otherwise she is invisible. If she's hungry, she appears between the lily pots whle the other fish are scarfing fish food. She will grab a worm and then dart off to eat it away from the koi. Usually each afternoon she will return for 3-4 more worms. Then, I figure she's full because she won't take any more. She also likes white grubs and slugs. She is growing and appears healthy.